Capsule endoscope system, operating method of image display, and computer-readable recording medium

ABSTRACT

A capsule endoscope system includes: a capsule endoscope including a first and a second imaging units; an image display that displays images captured by the first and second imaging units; a control unit that determines a moving direction of the capsule endoscope during imaging, specifies one of the imaging units which faces the moving direction of the capsule endoscope during imaging, and determines the posture of the capsule endoscope; and a display control unit that generates a display screen, arranges the image captured by the imaging unit facing the moving direction in a first display region in the display screen, arranges the image captured by the other imaging unit in a second display region in the display screen, and changes the positions of the first and second display regions according to the determination result of the position of the capsule endoscope.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a continuation of PCT international application Ser.No. PCT/JP2012/067489 filed on Jul. 9, 2012 which designates the UnitedStates, incorporated herein by reference, and which claims the benefitof priority from Japanese Patent Applications No. 2011-161322, filed onJul. 22, 2011, incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a capsule endoscope system, a method ofoperating an image display, and a computer-readable recording mediumwhich display images acquired by a capsule endoscope introduced into asubject.

2. Description of the Related Art

In recent years, in the field of endoscopes, a swallow-type capsuleendoscope has been developed. The capsule endoscope is introduced intothe body of the subject (patient) from the mouth and sequentiallycaptures the images of the lumens (alimentary canals), such as theesophagus, the stomach, the small intestine, and the large intestine,while is being moved in the lumens by the peristaltic motion until it isnaturally eliminated from the subject. Image data generated from theimage captured by the capsule endoscope is sequentially transmitted bywireless communication, is received by a receiving device which isprovided outside the subject, and is then stored in a memory which isprovided in the receiving device. The image data is transmitted to animage display after examination ends, predetermined image processing isperformed on the image data, and the processed image data is displayedas an in-vivo image on a display. The user (for example, a doctor)observes the in-vivo image displayed on the display, finds anabnormality, and specifies the position (organ) of the abnormality inthe subject. This process is referred to as observation.

As the capsule endoscope, the followings have been developed: amonocular capsule endoscope in which an imaging unit including animaging element and an illumination element is provided on one side of acapsule in the longitudinal direction; and a pantoscopic (binocular)capsule endoscope in which imaging units are provided on both sides of a(for example, see Japanese Patent Application Laid-open No. 2009-89910,Japanese Patent Application Laid-open No. 2007-282794, Japanese PatentApplication Laid-open No. 2006-288869, and Japanese Patent ApplicationLaid-open No. 2010-17555). The pantoscopic capsule endoscope can captureimages on the front and rear sides of the capsule in the longitudinaldirection.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a capsule endoscopesystem includes: a capsule endoscope that includes a first imaging unitwhich captures an image in a first direction and a second imaging unitwhich captures an image in a second direction different from the firstdirection, is introduced into a subject, and captures an in-vivo imageof the subject; an image display that displays an image based on imagedata obtained from the in-vivo images of the subject captured by thefirst and second imaging units; a control unit that determines a movingdirection of the capsule endoscope during imaging, specifies one of thefirst and second imaging units which faces the moving direction of thecapsule endoscope during imaging, and determines the position of thecapsule endoscope; and a display control unit that generates a displayscreen including a first display region in which an image in the movingdirection of the capsule endoscope is arranged and a second displayregion in which an image in a direction opposite to the moving directionof the capsule endoscope is arranged, arranges, in the first displayregion, an image based on the image data acquired by the imaging unitwhich is specified to face the moving direction by the control unit,arranges, in the second display region, an image based on the image dataacquired by the other imaging unit, and changes the positions of thefirst and second display regions according to the determination resultof the position of the capsule endoscope.

According to another aspect of the present invention, a method ofoperating an image display that displays an image corresponding to imagedata obtained by a capsule endoscope which includes a first imaging unitcapturing an image in a first direction and a second imaging unitcapturing an image in a second direction different from the firstdirection, is introduced into a subject, and captures an in-vivo imageof the subject includes: determining a moving direction of the capsuleendoscope during imaging, specifying one of the first and second imagingunits which faces the moving direction of the capsule endoscope duringimaging, and determining the posture of the capsule endoscope;generating a display screen which includes a first display region inwhich an image in the moving direction of the capsule endoscope isarranged and a second display region in which an image in a directionopposite to the moving direction of the capsule endoscope is arranged,and on which an image based on the image data acquired by the imagingunit which is specified to face the moving direction is arranged in thefirst display region, an image based on the image data acquired by theother imaging unit is arranged in the second display region, and thepositions of the first and second display regions are changed accordingto the determination result of the position of the capsule endoscope;and displaying the generated display screen.

According to still another aspect of the present invention, acomputer-readable recording medium having stored thereon an executableimage display program that causes an image display to display an imagecorresponding to image data obtained by a capsule endoscope whichincludes a first imaging unit capturing an image in a first directionand a second imaging unit capturing an image in a second directiondifferent from the first direction, is introduced into a subject, andcaptures an in-vivo image of the subject and causes a processor toperform: determining a moving direction of the capsule endoscope duringimaging, specifying one of the first and second imaging units whichfaces the moving direction of the capsule endoscope during imaging, anddetermining the posture of the capsule endoscope; generating a displayscreen which includes a first display region in which an image in themoving direction of the capsule endoscope is arranged and a seconddisplay region in which an image in a direction opposite to the movingdirection of the capsule endoscope is arranged, and on which an imagebased on the image data acquired by the imaging unit which is specifiedto face the moving direction is arranged in the first display region, animage based on the image data acquired by the other imaging unit isarranged in the second display region, and the positions of the firstand second display regions are changed according to the determinationresult of the position of the capsule endoscope; and displaying thegenerated display screen.

The above and other features, advantages and technical and industrialsignificance of this invention will be better understood by reading thefollowing detailed description of presently preferred embodiments of theinvention, when considered in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of the schematic structureof a capsule endoscope system according to a first embodiment of theinvention;

FIG. 2 is a longitudinal cross-sectional view illustrating the schematicstructure of a capsule endoscope illustrated in FIG. 1;

FIG. 3 is a block diagram illustrating the schematic structure of thecapsule endoscope illustrated in FIG. 2;

FIG. 4 is a schematic diagram illustrating an aspect of the movement ofthe capsule endoscope in a subject;

FIG. 5 is a block diagram illustrating the schematic structure of areceiving device illustrated in FIG. 1;

FIG. 6 is a block diagram illustrating the schematic structure of animage display illustrated in FIG. 1;

FIG. 7 is a schematic diagram illustrating an observation screendisplayed on a display unit illustrated in FIG. 6;

FIG. 8 is a flowchart illustrating the operation of the image display inan in-vivo image display process;

FIGS. 9A and 9B are diagrams illustrating a method of estimating theamount of movement of the capsule endoscope;

FIGS. 10A to 10D are diagrams illustrating an in-vivo image displaymethod according to the first embodiment;

FIGS. 11A and 11D are schematic diagrams illustrating an in-vivo imagedisplay method according to a second embodiment;

FIGS. 12A to 12D are schematic diagrams illustrating an in-vivo imagedisplay method according to a third embodiment;

FIGS. 13A and 13B are schematic diagrams illustrating an in-vivo imagedisplay method according to a fourth embodiment;

FIGS. 14A to 14D are schematic diagrams illustrating an in-vivo imagedisplay method according to Modification 4-1;

FIGS. 15A to 15C are schematic diagrams illustrating an example of thedisplay of in-vivo images according to Modification 4-2;

FIGS. 16A and 16B are diagrams illustrating the coordinates of a capsuleendoscope according to a fifth embodiment;

FIGS. 17A to 17C are schematic diagrams illustrating an example of thedisplay of in-vivo images according to the fifth embodiment;

FIG. 18 is a schematic diagram illustrating an example of the display ofin-vivo images according to Modification 5-1;

FIGS. 19A to 19C are schematic diagrams illustrating an in-vivo imagedisplay method according to Modification 5-2;

FIGS. 20A and 20B are diagrams illustrating the coordinates of a capsuleendoscope according to a sixth embodiment;

FIGS. 21A to 21C are schematic diagrams illustrating an example of thedisplay of in-vivo images according to the sixth embodiment;

FIGS. 22A to 22C are schematic diagrams illustrating an example of thedisplay of in-vivo images according to Modification 6-2;

FIGS. 23A to 23C are schematic diagrams illustrating a first displayexample of in-vivo images according to a seventh embodiment;

FIGS. 24A to 24C are schematic diagrams illustrating a second displayexample of the in-vivo images according to the seventh embodiment; and

FIGS. 25A to 25C are schematic diagrams illustrating a third displayexample of the in-vivo images according to the seventh embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a capsule endoscope system, a method of operating an imagedisplay, and a computer-readable recording medium according toembodiments of the invention will be described with reference to theaccompanying drawings. In the following description, for example, animage display which displays an image (hereinafter, referred to as anin-vivo image) acquired by a capsule endoscope that is introduced intothe body of a subject and captures the image of the inside of the lumen(alimentary canal) is given as an example. However, the invention is notlimited by the embodiments. In addition, in the following description,the drawings schematically illustrate the shape, size, and positionalrelationship of components such that the content of the invention can beunderstood. Therefore, the invention is not limited only to the shape,size, and positional relationship of the components illustrated in thedrawings.

First Embodiment

FIG. 1 is a diagram illustrating an example of the schematic structureof a capsule endoscope system according to a first embodiment of theinvention. The capsule endoscope system illustrated in FIG. 1 includes acapsule endoscope 2 that is introduced into the body of a subject 1,captures an in-vivo image, and wirelessly transmits image datacorresponding to the in-vivo image, a receiving device 3 that receivesthe image data wirelessly transmitted from the capsule endoscope 2through an antenna unit 30 including receiving antennas 30 a to 30 h,and an image display 5 that displays the in-vivo image based on theimage data which is transmitted from the receiving device 3 through acradle 4. Each of the receiving antennas 30 a to 30 h is implemented by,for example, a loop antenna and is arranged at a predetermined position(for example, a position corresponding to each organ in the subject 1which is a passage of the capsule endoscope 2) on the outer surface ofthe body of the subject 1.

FIG. 2 is a longitudinal cross-section view illustrating the schematicstructure of the capsule endoscope 2. FIG. 3 is a block diagramillustrating the schematic structure of the capsule endoscope 2. Thecapsule endoscope 2 is a pantoscopic capsule endoscope including aplurality of imaging units. In the first embodiment, the capsuleendoscope 2 includes two imaging units.

As illustrated in FIGS. 2 and 3, the capsule endoscope 2 includes acapsule-shaped casing 11 that can be introduced into the lumens of thesubject 1, two imaging units 12 a and 12 b that are accommodated in thecapsule-shaped casing 11 and capture images in the front-rear direction,an acceleration sensor 13 serving as a unit for detecting the posture ofthe capsule endoscope 2, signal processing and control units 21 a and 21b corresponding to the imaging units 12 a and 12 b, and a transmissionmodule 28 and a transmitting antenna 29 that transmit image datagenerated by the signal processing and control units 21 a and 21 b. Inaddition, the capsule endoscope 2 includes a battery, circuit componentsand the like (not illustrated). The capsule-shaped casing 11 has a sizethat is swallowable from the mouth of the subject 1 and includes endcovers 11 a and 11 b that have a substantially hemispherical shape andare transparent or translucent and a middle cover 11 c that has acylindrical shape and is made of a colored material which does nottransmit visible light. The covers are elastically coupled to each otherto form an outer casing whose inside is liquid-tightly sealed.

The imaging unit 12 a includes a plurality of illumination elements 14a, such as LEDs that emit illumination light for illuminating the insideof the subject 1 (lumen) through the end cover 11 a, an imaging element15 a, such as a CCD or a CMOS that receives the reflected light of theillumination light and captures the in-vivo image of the subject, and animaging lens 16 a that forms the in-vivo image of the subject on theimaging element 15 a, and captures an image in the end direction of theend cover 11 a.

The imaging unit 12 b includes a plurality of illumination elements 14b, such as LEDs that emit illumination light for illuminating the insideof the subject through the end cover 11 b, an imaging element 15 b, suchas a CCD or a CMOS that receives the reflected light of the illuminationlight and captures the in-vivo image of the subject, and an imaging lens16 b that forms the in-vivo image of the subject on the imaging element15 b, and captures an image in the end direction of the end cover 11 b.

The acceleration sensor 13 is provided, for example, in the vicinity ofthe center of the capsule-shaped casing 11, detects acceleration in atriaxial direction which is applied to the capsule-shaped casing 11, andoutputs the detected signal. In addition, the positional relationshipbetween the acceleration sensor 13 and the imaging units 12 a and 12 bis set and stored in advance. In this way, it is possible to determinethe posture of the capsule endoscope 2 on the basis of the detectedsignal from the acceleration sensor 13 and specify the positionalrelationship (for example, the upper side/the lower side and the frontside/the rear side) of the imaging units 12 a and 12 b.

The signal processing and control unit 21 a is provided so as tocorrespond to the imaging unit 12 a and includes an illumination elementdriving circuit 22 a that drives the illumination element 14 a, animaging element driving circuit 23 a that drives the imaging element 15a, a signal processing unit 24 a that performs predetermined signalprocessing for the signal output from the imaging element 15 a, and acontrol unit 26 a that controls the operations of the units. The signalprocessing unit 24 a performs predetermined signal processing, such as acorrelated double sampling process, an amplification process, an A/Dconversion process, and a multiplexing process, for the signal outputfrom the imaging element 15 a to generate image data corresponding to animaging region in the subject. The control unit 26 a includes a timinggenerator and synchronous generator (TG, SG) 25 a that generates variouskinds of timing signals or synchronous signals and controls, forexample, the operation of the driving circuits 22 a and 23 a and thesignal processing unit 24 a or the operation timing thereof, based onthe timing signals or the synchronous signals generated by the timinggenerator and synchronous generator 25 a. In addition, the control unit26 a performs predetermined signal processing (for example, the A/Dconversion process) for the detected signal output from the accelerationsensor 13 and stores the processed signal as information about theposture of the capsule endoscope 2 so as to be associated with imagedata corresponding to when the detected signal is detected.

The signal processing and control unit 21 b is provided so as tocorrespond to the imaging unit 12 b and includes an illumination elementdriving circuit 22 b that drives the illumination element 14 b, animaging element driving circuit 23 b that drives the imaging element 15b, a signal processing unit 24 b that performs predetermined signalprocessing for the signal output from the imaging element 15 b, and acontrol unit 26 b that controls the operation of the units based on thetiming signals or the synchronous signals generated by a timinggenerator and synchronous generator (TG, SG) 25 b. The operation of eachunit is the same as that in the signal processing and control unit 21 a.

After the capsule endoscope 2 is swallowed from the mouth of the subject1, it is moved into a lumen 1 a of the subject 1 by, for example, theperistaltic motion of the organs, as illustrated in FIG. 4. While thecapsule endoscope 2 is being moved, the imaging units 12 a and 12 bsequentially capture the images of parts of the body (for example, theesophagus, the stomach, the small intestine, and the large intestine) ata predetermined time interval (for example, an interval of 0.5 seconds)and the acceleration sensor 13 detects acceleration along the axis L ofthe capsule endoscope 2 and two axes perpendicular to the axis L. InFIG. 4, an arrow g indicates the direction of gravity acceleration. Theobtained image data and related information (for example, informationabout the posture) are sequentially transmitted to the receiving device3.

FIG. 5 is a block diagram illustrating the structure of the receivingdevice 3. As illustrated in FIG. 5, the receiving device 3 includes areceiving unit 31 that sequentially receives the image data and therelated information wirelessly transmitted from the capsule endoscope 2through the antenna unit 30, a signal processing unit 32 that controlsthe operation of each unit in the receiving device 3 and performspredetermined image processing for the received image data, a memory 33that stores the processed image data and related information, aninterface (I/F) unit 34 that transmits the image data and the relatedinformation stored in the memory 33 to the image display 5 through thecradle 4, an operation unit 35 that is used by the user to input variousoperation instructions or settings to the receiving device 3, a displayunit 36 that notifies or displays various kinds of information to theuser, a gyro sensor 37 serving as a posture detecting unit of thereceiving device 3, and a battery 38 that supplies power to each of theabove-mentioned units.

The gyro sensor 37 detects the angular velocity of the receiving device3 and is provided in order to determine the posture (for example, astanding posture or a recumbent posture) of the receiving device 3, thatis, the posture of the subject 1 with the receiving device 3. The signalprocessing unit 32 performs predetermined signal processing (forexample, A/D conversion) for the signal detected by the gyro sensor 37and the processed detected signal is stored as information about theposture of the subject 1 so as to be associated with the image datacorresponding to when the detection signal is detected (for example,received at that time).

After the capture of the images by the capsule endoscope 2 ends, thereceiving device 3 is detached from the subject 1 and is then set to thecradle 4 which is connected to, for example, a USB port of the imagedisplay 5. Then, the receiving device 3 is connected to the imagedisplay 5 and the image data and the related information stored in thememory 33 are transmitted to the image display 5.

The transmission of, for example, the image data to the image display 5is not limited to the method of transmitting the image data through thecradle 4. For example, when the image data stored in a server isprocessed, it may be acquired through a communicate device connected tothe server. When image data stored in a portable recording medium, suchas a CD-R or a DVD-R, is processed, for example, a reading deviceprovided in the image display 5 may read the image data from therecording medium. Alternatively, a medical observation device may beconnected to the image display 5 and image data may be directly acquiredfrom the medical observation device.

FIG. 6 is a block diagram illustrating the structure of the imagedisplay 5. The image display 5 is implemented by, for example, aworkstation or a personal computer including a display screen such as amonitor.

As illustrated in FIG. 6, the image display 5 includes an interface(I/F) unit 51 that receives input image data corresponding to thein-vivo image, an operation unit 52 that is used by the user to inputvarious kinds of information or commands, a temporary storage unit 53that temporarily stores the image data input from the interface unit 51,an image processing unit 54 that performs image processing for the imagedata stored in the temporary storage unit 53, a storage unit 55 thatstores the processed image data, a control unit 56 that controls theoperation of each unit in the image display 5 and performs variousdetermination processes on the basis of information related to the imagedata, a display control unit 57 that generates an observation screen onwhich in-vivo images are arranged in a predetermined format, and adisplay unit 58 that displays the observation screen under the controlof the display control unit 57.

The interface unit 51 includes a connection port (for example, a USBport) to an external device (for example, a reading device which readsimage data from a portable recording medium) and receives the input ofsignals indicating the image data which is input through the connectionport and information related to the image data.

The operation unit 52 is implemented by, for example, an input device,such as a keyboard, a mouse, a touch panel, or various kinds ofswitches. The operation unit 52 receives the input of an operationsignal corresponding to the operation of the user and outputs theoperation signal to the control unit 56 through the interface unit 51.

The temporary storage unit 53 is implemented by a volatile memory, suchas a DRAM or an SRAM, and temporarily stores the image data which isinput through the interface unit 51 and information related to the imagedata. Alternatively, instead of the temporary storage unit 53, arecording medium, such as an HDD, an MO, a CD-R, or a DVD-R, and adriving device that drives the recording medium may be provided, and theimage data input from the interface unit 51 may be temporarily stored inthe recording medium.

The image processing unit 54 performs image processing, such as whitebalance processing, demosaicing, color conversion, density conversion(for example, gamma conversion), smoothing (for example, noise removal),or sharpening (for example, edge emphasis), for the image data stored inthe temporary storage unit 53 to generate display image datacorresponding to a series of images.

The storage unit 55 is implemented by a semiconductor memory, such as aflash memory, a RAM, or a ROM, or a recording medium, such as an HDD, anMO, a CD-R, or a DVD-R, and a driving device that drives the recordingmedium. The storage unit 55 includes a program storage unit 551 thatstores a program for operating the image display 5 and for causing theimage display 5 to perform various functions and data which is usedduring the execution of the program and an image data storage unit 552that stores the image data and the related information. Specifically,the program storage unit 551 stores an image display program fordisplaying an image corresponding to the image data which is acquired bythe capsule endoscope 2 on the image display 5 in a predeterminedformat.

The control unit 56 is implemented by hardware, such as a CPU, reads theprogram stored in the program storage unit 551, transmits, for example,instructions or data to each unit of the image display 5 according tothe image data and the related information, or various operation signalsinput through the interface unit 51, and controls the overall operationof the image display 5. In addition, the control unit 56 includes amoving direction determining unit 561 that determines the direction inwhich the capsule endoscope 2 moves at the time when each in-vivo imageis captured, an imaging unit specifying unit 562 that specifies animaging unit which faces the moving direction and an imaging unit whichfaces a direction opposite to the moving direction of the imaging units12 a and 12 b in the capsule endoscope 2 based on the determinationresult of the moving direction determining unit 561, and a posturedetermining unit 563 that determines the posture of the capsuleendoscope 2 based on information about the posture of the capsuleendoscope 2 which is associated with the image data. The posture of thecapsule endoscope 2 means, for example, the positional relationshipbetween the imaging units 12 a and 12 b in the vertical direction or thedepth direction with respect to a predetermined coordinate axis.Examples of the coordinate axis include two axes perpendicular to themoving direction of the capsule endoscope 2 and the gravity accelerationdirection.

The display control unit 57 generates an observation screen on which twoin-vivo images captured by the two imaging units 12 a and 12 b arearranged, using the image data stored in the image data storage unit552, and displays the observation screen on the display unit 58.

The display unit 58 is implemented by a display device, such as a CRTdisplay, a liquid crystal display, or an EL display. The display unit 58displays the observation screen or other screens in a predeterminedformat under the control of the display control unit 57.

FIG. 7 is a diagram schematically illustrating an example of theobservation screen which is generated by the display control unit 57 andis then displayed on the display unit 58. As illustrated in FIG. 7, anobservation screen 100 includes a patient information display region 101in which patient information for identifying the subject 1, which is apatient, is displayed, an examination information display region 102 inwhich examination information for identifying examination for thesubject 1 is displayed, a reproducing operation button group 103 thatreceives the input of an operation for reproducing the in-vivo image,and an image display region 110 in which a series of in-vivo images isreproduced and displayed. The patient information includes, for example,a patient ID, a patient name, and the sex of the patient. In addition,the examination information includes, for example, the name of thehospital where the patient is examined, examination date and time, andthe serial number of the capsule endoscope 2 used.

The image display region 110 includes two display regions 111 and 112 inwhich the in-vivo images captured by the imaging units 12 a and 12 b arearranged. Of the two display regions 111 and 112, the display region 111is set as a region in which the in-vivo image facing the movingdirection is arranged and the display region 112 is set as a region inwhich the in-vivo image facing the direction opposite to the movingdirection of the capsule endoscope 2 is arranged. In the firstembodiment, the position of the display region 111 is fixed to the leftside of the image display region 110 and the position of the displayregion 112 is fixed to the right side of the image display region 110.

Next, an in-vivo image display process according to the first embodimentwill be described. FIG. 8 is a flowchart illustrating the operation ofthe image display 5 in the in-vivo image display process.

First, in Step S01, the control unit 56 reads the image data of thein-vivo image from the image data storage unit 552.

Then, in Step S02, the moving direction determining unit 561 determinesthe moving direction of the capsule endoscope 2 at the time when thein-vivo image, which is a display target, is captured. In the firstembodiment, the moving direction is a direction from the mouth to theanus of the subject 1 along the length direction of the lumen. Variousknown methods may be used as a method of determining the movingdirection. Next, for example, a method of determining the movingdirection on the basis of the amount of movement of the in-vivo imagewill be described.

First, the moving direction determining unit 561 estimates the amount ofmovement of the capsule endoscope 2 between the capture time t(i) of ani-th (i=1, 2, . . . ) in-vivo image G_(i), which is a display target,and the capture time t(i+Δ) of the next in-vivo image G_(i+Δ) on thebasis of the in-vivo images G_(i) and G_(i+Δ). The interval Δ (Δ is aninteger) between the in-vivo images is set to a relatively large value.The reason is as follows. Since the capsule endoscope 2 moves step bystep while reciprocating due to the influence of, for example, theperistaltic motion of the subject 1, the influence of the localreciprocation is excluded and the global moving direction (that is, thedirection from the mouth to the anus) of the capsule endoscope 2 isdetected. Therefore, the time interval between the capture time t(i) andthe capture time t(i+Δ) may be set to a relatively large value. Forexample, the average period of the peristaltic motion of the subject 1may be acquired in advance and the time interval may be set based on theaverage period. Specifically, when the average number of peristalticmotions of the subject 1 per minute is 6, the time interval is set to,about, 10 seconds which are the average period of the peristalticmotion.

FIGS. 9A and 9B are diagrams illustrating the method of estimating theamount of movement of the capsule endoscope 2. FIG. 9A illustrates theimaging condition model of the capsule endoscope 2 which captures thein-vivo image G_(i) at the capture time t(i) and FIG. 9B illustrates theimaging condition model of the capsule endoscope 2 which captures thein-vivo image G_(i+Δ) at the capture time t(i+Δ). The in-vivo imagesG_(i) and G_(i+Δ) include a corresponding feature structure 61. Thefeature structure 61 is a structure which characterizes a local part onthe mucous membrane of the lumen and specifically corresponds to, forexample, the blood vessel which is seen through the wrinkle or surfaceof the mucous membrane of the lumen.

In FIGS. 9A and 9B, letter D indicates a feature structure distanceobtained by projecting a distance from the capsule endoscope 2 to thefeature structure 61 on the mucous membrane of the lumen at the capturetime t(i) onto the inner wall of the lumen and letter D′ indicates afeature structure distance obtained by projecting a distance from thecapsule endoscope 2 to the feature structure 61 on the mucous membraneof the lumen at the capture time t(i+Δ). Letter O indicates an opticalcenter corresponding to the principal point of an optical system, suchas a lens of the capsule endoscope 2. For example, the average radius ofthe lumen is used as the radius R of the lumen.

In addition, image coordinates 63 a illustrated in FIG. 9A are thecoordinates of the in-vivo image G_(i) projected onto the imagingelement of the capsule endoscope 2. The image coordinates 63 a are in acoordinate system which has a point intersecting an optical axis 62 ofthe capsule endoscope 2 as the origin and the gap from the opticalcenter O of the capsule endoscope 2 to the imaging element is a distancef. It is assumed that the coordinates of the center of a structureregion in which the feature structure 61 of the in-vivo image obtainedby the imaging situation model is seen are structure region centercoordinates T (xT, yT) and the coordinates of the center of gravity of adeep part of the lumen in the in-vivo image are lumen deep part gravitycenter coordinates C (xC, yC). In addition, it is assumed that an angleθ is the angle formed between a vector OC from the optical center O inthe direction 64 of the center of gravity of the deep part of the lumenand a vector OT from the optical center O to the feature structure 61 atthe capture time t(i).

Similarly, image coordinates 63 b illustrated in FIG. 9B are thecoordinates of the in-vivo image G_(i+Δ). The image coordinates 63 b arein the coordinate system which has the point intersecting the opticalaxis 62 of the capsule endoscope 2 as the origin and the gap from theoptical center O of the capsule endoscope 2 to the imaging element isthe distance f. It is assumed that the coordinates of the center of acorresponding region in which the feature structure 61 of the in-vivoimage obtained by the imaging situation model is seen are correspondingregion center coordinates T′ (xT′, yT′) and the coordinates of thecenter of gravity of the deep part of the lumen in the in-vivo image arelumen deep part gravity center coordinates C′ (xC′, yC′). In addition,it is assumed that an angle θ′ is the angle formed between a vector OC′from the optical center O in the direction 64 of the center of gravityof the deep part of the lumen and a vector OT′ from the optical center Oto the feature structure 61 at the capture time t(i+Δ).

In the imaging condition model illustrated in FIG. 9B, a variation inthe imaging position (the position of the capsule endoscope 2) and avariation in the imaging direction occur, as compared to the imagingsituation model illustrated in FIG. 9A.

The following Expression 1 is obtained from the feature structuredistance D, the structure region center coordinates T, the lumen deeppart gravity center coordinates C, the distance f, and the lumen radiusR in the imaging situation model illustrated in FIG. 9A:

$\begin{matrix}{{\frac{R}{D} = {{\tan \; \theta} = \frac{\sqrt{1 - {\cos^{2}\theta}}}{\cos \; \theta}}}{{\cos \; \theta} = {\frac{\overset{\rightarrow}{OT} \cdot \overset{\rightarrow}{OC}}{{\overset{\rightarrow}{OT}} \times {\overset{\rightarrow}{OC}}} = \frac{{\left( {{xT} \times \delta} \right) \times \left( {{xC} \times \delta} \right)} + {\left( {{yT} \times \delta} \right) \times \left( {{yC} \times \delta} \right)} + f^{2}}{\sqrt{\left( {{xT} \times \delta} \right)^{2} + \left( {{yT} \times \delta} \right)^{2} + f^{2}} \times \sqrt{\left( {{xC} \times \delta} \right)^{2} + \left( {{yC} \times \delta} \right)^{2} + f^{2}}}}}} & (1)\end{matrix}$

(where, δ indicates the pitch between the imaging elements of thecapsule endoscope 2).

The distance f and the value of each camera parameter of the pitch δbetween the imaging elements are acquired in advance.

Similarly, the following Expression 2 is obtained from the featurestructure distance D′, the corresponding region center coordinates T′,the lumen deep part gravity center coordinates C′, the distance f, andthe lumen radius R in the imaging situation model illustrated in FIG.9B:

$\begin{matrix}{{\frac{R}{D^{\prime}} = \frac{\sqrt{1 - {\cos^{2}\theta^{\prime}}}}{\cos \; \theta^{\prime}}}{{\cos \; \theta^{\prime}} = {\frac{\overset{\rightarrow}{{OT}^{\prime}} \cdot \overset{\rightarrow}{{OC}^{\prime}}}{{\overset{\rightarrow}{{OT}^{\prime}}} \times {\overset{\rightarrow}{{OC}^{\prime}}}} = {\quad\frac{{\left( {{xT}^{\prime} \times \delta} \right) \times \left( {{xC}^{\prime} \times \delta} \right)} + {\left( {{yT}^{\prime} \times \delta} \right) \times \left( {{yC}^{\prime} \times \delta} \right)} + f^{2}}{\begin{matrix}{\sqrt{\left( {{xT}^{\prime} \times \delta} \right)^{2} + \left( {{yT}^{\prime} \times \delta} \right)^{2} + f^{2}} \times} \\\sqrt{\left( {{xC}^{\prime} \times \delta} \right)^{2} + \left( {{yC}^{\prime} \times \delta} \right)^{2} + f^{2}}\end{matrix}}}}}} & (2)\end{matrix}$

The following Expression 3 is obtained from Expression 1 and Expression2:

$\begin{matrix}{{\frac{R}{D} - \frac{R}{D^{\prime}}} = {\frac{\sqrt{1 - {\cos^{2}\theta}}}{\cos \; \theta} - \frac{\sqrt{1 - {\cos^{2}\theta^{\prime}}}}{\cos \; \theta^{\prime}}}} & (3)\end{matrix}$

Expression 3 is changed to obtain the following Expression 4:

$\begin{matrix}{{D - D^{\prime}} = {\left( {\frac{\cos \; \theta}{\sqrt{1 - {\cos^{2}\theta}}} - \frac{\cos \; \theta^{\prime}}{\sqrt{1 - {\cos^{2}\theta^{\prime}}}}} \right) \times R}} & (4)\end{matrix}$

A value D-D′ which is given by Expression 4 is the difference betweenthe feature structure distances obtained by projecting the distancesfrom the capsule endoscope 2 to the feature structure 61 on the mucousmembrane of the lumen at the capture times t(i) and t(i+Δ) onto theinner wall of the lumen and corresponds to the amount of movement d ofthe capsule endoscope 2 from the capture time t(i) to the capture time(i+Δ) illustrated in FIG. 9B.

The moving direction determining unit 561 calculates the value D-D′ foreach feature structure included in the in-vivo images and calculates theaverage value of the values D-D′. The average value is estimated as theamount of movement of the capsule endoscope 2 from the capture time t(i)to the capture time t(i+Δ). Hereinafter, the average value of the valuesD-D′ is referred to as the amount of movement E.

The moving direction determining unit 561 calculates the amount ofmovement E for the in-vivo images captured by the imaging units 12 a and12 b. Then, the moving direction determining unit 561 determines thatthe direction of the imaging unit with the positive amount of movement Eis the moving direction.

The details of the method of estimating the amount of movement which isused as an example of the moving direction determining method in StepS02 are disclosed in Japanese Patent Application Laid-open No.2008-301877.

Then, in Step S03, the imaging unit specifying unit 562 specifies theimaging unit which faces the moving direction at the imaging time basedon the determination result of the moving direction determining unit561. Here, the imaging unit facing the moving direction includes theimaging unit satisfying cos α>0 (where α is the angle formed between themoving direction of the capsule endoscope 2 and the optical axis whenthe emission direction of illumination light is a positive direction).

As described above, when the amount of movement E is used to determinethe moving direction of the capsule endoscope 2, the process ofdetermining the moving direction and the process of specifying theimaging unit facing the moving direction may be performed at the sametime.

In Step S04, the display control unit 57 determines the arrangement ofthe in-vivo images captured by the imaging units 12 a and 12 b in theimage display region 110. That is, the in-vivo image captured by theimaging unit which is specified to face the moving direction is arrangedin the left (moving direction side) display region 111 and the in-vivoimage captured by the imaging unit which is specified to face thedirection opposite to the moving direction is arranged in the right (theside opposite to the moving direction) display region 112. In this way,the observation screen including the in-vivo images captured by the twoimaging units 12 a and 12 b is displayed on the display unit 58 (StepS05).

Next, the detailed arrangement of the in-vivo images in the imagedisplay region 110 will be described with reference to schematicdiagrams.

FIG. 10A is a schematic diagram illustrating the capsule endoscope 2that moves in the lumen 1 a of the subject 1. FIGS. 10B to 10D areschematic diagrams illustrating examples of the arrangement of thein-vivo images captured at positions P11, P12, and P13 illustrated inFIG. 10A. In the following description, the in-vivo image captured bythe imaging unit 12 a is referred to as an in-vivo image A and thein-vivo image captured by the imaging unit 12 b is referred to as anin-vivo image B. In addition, in the following description, the imagingunit 12 a is hatched for ease of recognition in the drawings. In FIGS.10B to 10D, the in-vivo image A is hatched in order to clarify thecorrespondence with the imaging unit 12 a.

As illustrated in FIG. 10A, the capsule endoscope 2 which has passedthrough the position P11 moves with the imaging unit 12 a facing theanus. In this case, as illustrated in FIG. 10B, in the image displayregion 110 corresponding to the position P11, the in-vivo image Acorresponding to the imaging unit 12 a is arranged in the display region111 which is disposed in the moving direction and the in-vivo image Bcorresponding to the imaging unit 12 b is arranged in the display region112 which is disposed in the direction opposite to the moving direction.

After passing through the position P11, the capsule endoscope 2 rotatesback and forth and passes through the position P12 with the imaging unit12 b facing the anus. In this case, as illustrated in FIG. 10C, in theimage display region 110 corresponding to the position P12, the in-vivoimage B corresponding to the imaging unit 12 b is arranged in thedisplay region 111 which is disposed in the moving direction and thein-vivo image A corresponding to the imaging unit 12 a is arranged inthe display region 112 which is disposed in the direction opposite tothe moving direction.

Then, the capsule endoscope 2 passes through the position P13 with theimaging unit 12 b facing the anus. In this case, in the image displayregion 110 corresponding to FIG. 10D, the in-vivo image B correspondingto the imaging unit 12 b is arranged in the display region 111 which isdisposed in the moving direction and the in-vivo image A correspondingto the imaging unit 12 a is arranged in the display region 112 which isdisposed in the direction opposite to the moving direction.

As described above, according to the first embodiment, on the screenincluding the first display region in which the image in the movingdirection of the capsule endoscope 2 is arranged and the second displayregion in which the image in the direction opposite to the movingdirection of the capsule endoscope 2 is arranged, the image based on theimage data acquired by the imaging unit which is specified to face themoving direction during imaging is displayed in the first displayregion, and the image based on the image data acquired by the otherimaging unit is arranged in the second display region. Therefore, theuser can visually know the direction of the images captured by twoimaging units or the moving direction of the capsule endoscope 2 withease.

That is, the in-vivo image of a part which is close to the anus than thecapsule endoscope 2 is constantly displayed in the display region 111 inthe moving direction which is arranged on the left side of the screenand the in-vivo image of a part which is closer to the mouth than thecapsule endoscope 2 is displayed in the display region 112 in thedirection opposite to the moving direction which is arranged on theright side of the screen. Therefore, the user can visually know thedirection (the anus side/the mouth side) of a part in the in-vivo imagewith ease. Therefore, even when observing a portion of the in-vivoimage, the user can visually know the direction of each in-vivo imagewhich is currently being displayed. In addition, since the user who isnot an expert can intuitively know the moving direction of the capsuleendoscope 2, it is possible to improve the efficiency of observation.

According to the first embodiment, since the in-vivo image including ananus-side part is constantly displayed on the same side, a rapid changein the background of one display region is reduced and it is possible toreduce the load (for example, an influence on the eye and fatigue) ofthe user during observation.

Second Embodiment

Next, a second embodiment of the invention will be described.

The structure of a capsule endoscope system according to the secondembodiment is the same as that illustrated in FIGS. 1 to 6. the secondembodiment differs from the first embodiment in the detailed operationof the moving direction determining unit 561.

The moving direction determining unit 561 detects, as the movingdirection of the capsule endoscope 2, the moving direction of thecapsule endoscope 2 at the moment when an in-vivo image is captured. Inthis case, it is possible to reflect the reciprocating motion of thecapsule endoscope 2 due to the peristaltic motion in the display of thein-vivo image. The imaging unit specifying unit 562 specifies an imagingunit which faces the moving direction and an imaging unit which faces adirection opposite to the moving direction, based on the determinationresult of the moving direction determining unit 561. The display controlunit 57 determines the arrangement of in-vivo images such that thein-vivo image captured by the imaging unit which is specified to facethe moving direction is arranged in the display region 111 disposed inthe moving direction and the in-vivo image captured by the imaging unitwhich is specified to face the direction opposite to the movingdirection is arranged in the display region 112 disposed in thedirection opposite to the moving direction.

In addition, similarly to the first embodiment, for example, the movingdirection determining unit 561 may determine the moving direction basedon the amount of movement E of the capsule endoscope 2. In this case,the interval Δ between the in-vivo images may be set to a small value(for example, Δ=1) and the amount of movement may be estimated. In thisway, it is possible to calculate the local moving direction of thecapsule endoscope 2. Alternatively, the moving direction determiningunit 561 may detect the moving direction of the capsule endoscope 2based on a detected signal which is detected by the acceleration sensor13 of the capsule endoscope 2.

Next, the detailed arrangement of the in-vivo images according to thesecond embodiment will be described with reference to schematicdiagrams.

(a) of FIG. 11A illustrates an aspect in which the capsule endoscope 2moves to the left side in the lumen 1 a with the imaging unit 12 afacing to the left side of (a) of FIG. 11A. In this case, as illustratedin (b) of FIG. 11A, an in-vivo image A captured by the imaging unit 12 ais arranged in a display region 121 which is disposed in the movingdirection. On the other hand, an in-vivo image B captured by an imagingunit 12 b is arranged in a display region 122 which is disposed in thedirection opposite to the moving direction.

(a) of FIG. 11B illustrates an aspect in which the capsule endoscope 2moves to the right side in the lumen 1 a with the imaging unit 12 bfacing to the right side of (a) of FIG. 11B. In this case, asillustrated in (b) of FIG. 11B, the in-vivo image B captured by theimaging unit 12 b is arranged in the display region 121 which isdisposed in the moving direction. On the other hand, the in-vivo image Acaptured by an imaging unit 12 a is arranged in the display region 122which is disposed in the direction opposite to the moving direction.

As described above, according to the second embodiment, the user canvisually know the direction of the in-vivo image with respect to thelocal moving direction of the capsule endoscope 2. In addition, thein-vivo image in the forward direction is constantly displayed in thedisplay region 121 which is disposed in the moving direction and thein-vivo image in the backward direction is constantly displayed in thedisplay region 122. Therefore, it is possible to reduce the burden (forexample, the flickering of image) of the user who observes the screen.Even when the capsule endoscope 2 repeatedly moves forward and backwardin the lumen 1 a, the user does not misunderstand the same lesion as adifferent lesion. Therefore, it is possible to improve the efficiency ofobservation.

Third Embodiment

Next, a third embodiment of the invention will be described.

The structure of a capsule endoscope system according to the thirdembodiment is the same as that illustrated in FIGS. 1 to 6. the thirdembodiment differs from the first embodiment in that the determinationresult of the posture determining unit 563 for the posture of thecapsule endoscope 2 is reflected in determining the arrangement ofin-vivo images on an observation screen.

In this case, the posture determining unit 563 calculates the posture ofthe capsule endoscope 2 based on information about the position of thecapsule endoscope 2 which is associated with the image data of thein-vivo image and determines the positional relationship between theimaging units 12 a and 12 b. The imaging unit specifying unit 562specifies an imaging unit which faces up and an imaging unit which facesdown at the imaging time, based on the determination result of theposture determining unit 563. A display control unit 57 sets a displayregion (hereinafter, referred to as an upper display region) of anin-vivo image indicating the upper side (that is, the upper wall of thelumen 1 a) of the capsule endoscope 2 and a display region (hereinafter,referred to as a lower display region) of an in-vivo image indicatingthe lower side (that is, the lower wall of the lumen 1 a) of the capsuleendoscope 2 to predetermined positions of the image display region 110.In addition, the display control unit 57 arranges the in-vivo imagecaptured by the imaging unit which is determined to face up in the upperdisplay region and arranges the in-vivo image captured by the imagingunit which is determined to face down in the lower display region, basedon the specification result of the imaging unit specifying unit 562.

Next, the detailed arrangement of the in-vivo images in the thirdembodiment will be described with reference to schematic diagrams. Asillustrated in FIG. 12A, the capsule endoscope 2 which has passedthrough a position P31 moves upward toward the imaging unit 12 a. Inthis case, as illustrated in FIG. 12B, in the image display region 110corresponding to the position P31, an in-vivo image A corresponding tothe imaging unit 12 a is arranged in an upper display region 131 and anin-vivo image B corresponding to the imaging unit 12 b is arranged in alower display region 132. In this way, a region 133′ corresponding to alesion 133 which is on the upper wall of the lumen 1 a is displayed inthe display region 131.

After passing through the position P31, the capsule endoscope 2 moves inthe lumen 1 a, with the imaging unit 12 a up. In this case, asillustrated in FIG. 12C, in the image display region 110 correspondingto the position P32, the in-vivo image A corresponding to the imagingunit 12 a is arranged in the upper display region 131 and the in-vivoimage B corresponding to the imaging unit 12 b is arranged in the lowerdisplay region 132. In this way, the region 133′ corresponding to thelesion 133 which is on the upper wall of the lumen 1 a is displayed inthe upper display region 131 and a region 134′ corresponding to a lesion134 which is on the lower wall of the lumen 1 a is displayed in thelower display region 132.

Then, the capsule endoscope 2 passes through a position P33, with theimaging unit 12 b slightly up. In this case, as illustrated in FIG. 12D,in the image display region 110 corresponding to the position P33, thein-vivo image B corresponding to the imaging unit 12 b is arranged inthe upper display region 131 and the in-vivo image A corresponding tothe imaging unit 12 a is arranged in the lower display region 132. Inthis way, a region 135′ corresponding to a lesion 135 which is on thelower wall of the lumen 1 a is displayed in the lower display region132.

As described above, according to the third embodiment, the in-vivoimages to be arranged in the upper display region 131 and the lowerdisplay region 132 are determined based on the positions of the imagingunits 12 a and 12 b. Therefore, the user can intuitively know theposition (the upper side or the lower side of the lumen) of a part ofinterest (for example, a lesion) in the lumen in the in-vivo image.

Fourth Embodiment

Next, a fourth embodiment of the invention will be described.

The structure of a capsule endoscope system according to the fourthembodiment is the same as that illustrated in FIGS. 1 to 6. the fourthembodiment differs from the second embodiment in that, in addition tothe moving direction of the capsule endoscope 2, the posture of thecapsule endoscope 2 is applied to determine the arrangement of in-vivoimages.

The posture determining unit 563 determines the positional relationshipbetween imaging units 12 a and 12 b based on information about theposture of the capsule endoscope 2 which is associated with the imagedata of the in-vivo image. An imaging unit specifying unit 562 specifiesthe imaging unit which faces the moving direction of the capsuleendoscope 2 and the imaging unit which faces the direction opposite tothe moving direction at the imaging time, based on the determinationresult of a moving direction determining unit 561. In addition, theimaging unit specifying unit 562 specifies the imaging unit which facesup and the imaging unit which faces down, based on the determinationresult of the posture determining unit 563. A display control unit 57arranges the in-vivo image captured by the imaging unit 12 a which isspecified to face the moving direction in a display region which isdisposed in the moving direction and arranges the imaging unit which isspecified to face the direction opposite to the moving direction in adisplay region which is disposed in the direction opposite to the movingdirection. In addition, the display control unit 57 changes thepositions of the display region which is disposed in the movingdirection and the display region which is disposed in the directionopposite to the moving direction in the image display region 110 in thevertical direction, based on the relative positional relationshipbetween the imaging units in the vertical direction.

Next, the detailed arrangement of the in-vivo images in the fourthembodiment will be described with reference to schematic diagrams. (a)of FIG. 13A illustrates an aspect in which the capsule endoscope 2 movesto the left side in the lumen 1 a, with the imaging unit 12 a facing tothe left side of (a) of FIG. 13A. The imaging unit 12 a is arrangedabove the imaging unit 12 b. In this case, as illustrated in (b) of FIG.13A, the in-vivo image A captured by the imaging unit 12 a is arrangedin a display region 141 which is disposed in the moving direction andthe position of the display region 141 shifts upward in the imagedisplay region 110. Since the imaging unit 12 b is arranged below theimaging unit 12 a, the in-vivo image B captured by the imaging unit 12 bis arranged in a display region 142 which is disposed in the directionopposite to the moving direction and the position of the display region142 shifts downward in the image display region 110. In this way, aregion 143′ corresponding to a lesion 143 which is on the upper wall ofthe lumen 1 a is displayed in the display region 141 which is disposedin the moving direction.

(a) of FIG. 13B illustrates an aspect in which the capsule endoscope 2moves to the right side in the lumen 1 a, with the imaging unit 12 bfacing to the right side of (a) of FIG. 13B. The imaging unit 12 b isarranged below the imaging unit 12 a. In this case, as illustrated in(b) of FIG. 13B, the in-vivo image B captured by the imaging unit 12 bis displayed in the display region 141 which is disposed in the movingdirection and the position of the display region 141 shifts downward inthe image display region 110. Since the imaging unit 12 a is arrangedabove the imaging unit 12 b, the in-vivo image A captured by the imagingunit 12 a is arranged in the display region 142 which is disposed in thedirection opposite to the moving direction and the position of thedisplay region 142 shifts upward in the image display region 110. Inthis way, the region 143′ corresponding to the lesion 143 is displayedin the display region 142 which is disposed in the direction opposite tothe moving direction.

As described above, according to the fourth embodiment, the user canvisually and intuitively know the observation direction (the upper sideor the lower side of the lumen 1 a) with respect to the moving directionof the capsule endoscope 2.

Modification 4-1

In the fourth embodiment, the position of the capsule endoscope 2 isapplied to the display of the in-vivo image according to the movingdirection of the capsule endoscope 2 which has been described in thesecond embodiment. However, the display of the in-vivo image to whichthe posture of the capsule endoscope 2 is applied may be performed forthe first embodiment. Hereinafter, the detailed arrangement of in-vivoimages according to Modification 4-1 will be described with reference toFIGS. 14A to 14D. In Modification 4-1, the display region 141 disposedin the moving direction (on the anus side) is set to the left side ofthe image display region 110 and the display region 142 disposed in thedirection (on the mouth side) opposite to the moving direction is set tothe right side of the image display region 110.

As illustrated in FIG. 14A, the capsule endoscope 2 which has passedthrough a position P41 moves with the imaging unit 12 a facing the anus.In this case, as illustrated in FIG. 14B, the in-vivo image A capturedby the imaging unit 12 a is displayed in the display region 141 disposedin the moving direction and the in-vivo image B captured by the imagingunit 12 b is arranged in the display region 142 disposed in thedirection opposite to the moving direction. The positions of the displayregions 141 and 142 are rotated and adjusted about a central axis 144according to the positional relationship between the imaging units 12 aand 12 b. Specifically, the imaging unit 12 a is slightly lower than theimaging unit 12 b. Therefore, the positions of the display regions 141and 142 are rotated in a counterclockwise direction about the centralaxis 144 such that the in-vivo image A shifts downward and the in-vivoimage B shifts upward and are then set in this state.

The capsule endoscope 2 which has passed through a position P42 moveswith the imaging unit 12 b facing the anus. In this case, as illustratedin FIG. 14C, the in-vivo image B is arranged in the display region 141disposed in the moving direction and the in-vivo image A is arranged inthe display region 142 disposed in the direction opposite to the movingdirection. At the position P42, the inclination of the capsule endoscope2 with respect to the horizontal direction is more than that at theposition P41 and the difference between the positions of the imagingunit 12 a and the imaging unit 12 b in the vertical direction is morethan that at the position P41. Therefore, the positions of the displayregions 141 and 142 are greatly rotated and adjusted about the centralaxis 144 in the range in which the positional relationship between thedisplay regions 141 and 142 in the horizontal direction is not reversed.

The capsule endoscope 2 which has passed through a position P43 moveswith the imaging unit 12 b facing the anus. In this case, as illustratedin FIG. 14D, the in-vivo image B is arranged in the display region 141disposed in the moving direction and the in-vivo image A is arranged inthe display region 142 disposed in the direction opposite to the movingdirection. At the position P43, contrary to the position P42, theimaging unit 12 b is arranged above the imaging unit 12 a. Therefore,the positions of the display regions 141 and 142 are rotated in theclockwise direction about the central axis 144 such that the in-vivoimage B shifts upward and the in-vivo image A shifts downward and arethen set in this state.

Modification 4-2

The capsule endoscope system may be configured such that the user canknow the local moving direction of the capsule endoscope 2 in thedisplay of the in-vivo image based on the moving direction of thecapsule endoscope 2 from the mouth to the anus of the subject 1 and theposition of the capsule endoscope 2. Next, the detailed arrangement ofin-vivo images according to Modification 4-2 will be described withreference to FIGS. 15A to 15C. In Modification 4-2, the display region141 disposed in the moving direction (on the anus side) is set on theleft side of the image display region 110 and the display region 142disposed in the direction (on the mouth side) opposite to the movingdirection is set on the right side of the image display region 110.

(a) of FIG. 15A illustrates an aspect in which the capsule endoscope 2stays at one point, with the imaging unit 12 a facing the anus and theupper side. In this case, as illustrated in (b) of FIG. 15A, the in-vivoimage captured by the imaging unit 12 a is arranged in the displayregion 141 disposed in the moving direction and the in-vivo imagecaptured by the imaging unit 12 b is arranged in the display region 142disposed in the direction opposite to the moving direction. In addition,the relative position of the display regions 141 and 142 in the verticaldirection is determined in correspondence with the positionalrelationship between the imaging units 12 a and 12 b. In this case, inorder to make the user recognize that the capsule endoscope 2 does notmove in any direction, gauges 146 a to 146 c, which are indicators forthe position of a central axis 145 between the display regions 141 and142, may be displayed in the image display region 110. In FIG. 15A, theposition of the central axis 145 corresponds to the gauge 146 b which isarranged at the center of the image display region 110.

(a) of FIG. 15B illustrates an aspect in which the capsule endoscope 2moves to the mouth, with the imaging unit 12 a facing the anus and theupper side. In this case, as illustrated in (b) of FIG. 15B, the in-vivoimages A and B are arranged in the display regions 141 and 142,respectively, and the positions of the display regions 141 and 142 inthe vertical direction are determined in correspondence with thepositional relationship between the imaging units 12 a and 12 b. Inaddition, the display regions 141 and 142 shift in a direction (to theright side of FIG. 15B) corresponding to the moving direction of thecapsule endoscope 2 while maintaining the positional relationshiptherebetween. In this case, since the central axis 145 between thedisplay regions 141 and 142 also shifts to the right side, the user canknow the moving direction of the capsule endoscope 2 with reference tothe gauges 146 a to 146 c. In FIG. 15B, the position of the central axis145 corresponds to the gauge 146 c which is on the right side of thecenter of the image display region 110. In addition, the amount of shiftof the display regions 141 and 142 may be changed depending on themoving speed of the capsule endoscope 2.

(a) of FIG. 15C illustrates an aspect in which the capsule endoscope 2moves to the anus in the same posture as that illustrated in FIG. 15B.In this case, as illustrated in (b) of FIG. 15C, the in-vivo images Aand B are arranged in the display regions 141 and 142, respectively, andthe positions of the display regions 141 and 142 in the verticaldirection are determined in correspondence with the positionalrelationship between the imaging units 12 a and 12 b. In addition, thedisplay regions 141 and 142 shift in a direction (to the left side ofFIG. 15C) corresponding to the moving direction of the capsule endoscope2 while maintaining the positional relationship therebetween. In FIG.15C, the position of the central axis 145 corresponds to the gauge 146 awhich is arranged on the left side of the center of the image displayregion 110.

According to Modification 4-2, the user can easily know the movingdirection of the capsule endoscope 2 to the mouth or the anus andintuitively know the posture of the capsule endoscope 2.

Fifth Embodiment

Next, a fifth embodiment of the invention will be described.

The structure of a capsule endoscope system according to the fifthembodiment is the same as that illustrated in FIGS. 1 to 6. the fifthembodiment is characterized in that the arrangement of in-vivo images onan observation screen is determined based on coordinates in a model inwhich the lumen 1 a of the subject 1 extends in a line.

An imaging unit specifying unit 562 specifies an imaging unit whichfaces a moving direction and an imaging unit which faces a directionopposite to the moving direction in a coordinate system in which thedirection from the mouth to the anus of the lumen 1 a is an X′-axis,based on the determination results of a moving direction determiningunit 561 and a posture determining unit 563. The posture determiningunit 563 determines the positional relationship between imaging units 12a and 12 b based on information about the posture of the capsuleendoscope 2. A display control unit 57 determines the arrangement of thein-vivo images in an image display region 110 based on the specificationresult of the imaging unit specifying unit 562 and the determinationresult of the posture determining unit 563.

Next, the detailed arrangement of the in-vivo images in the fifthembodiment will be described with reference to schematic diagrams. FIG.16A is a schematic diagram illustrating the capsule endoscope 2 whichmoves in the lumen 1 a. FIG. 16B is a schematic diagram illustrating themoving direction and position of the capsule endoscope 2 in a lumenmodel 1 a′ in which the direction of the lumen 1 a from the mouth to theanus is the X′-axis. In the lumen model 1 a′, any two axes perpendicularto the X′-axis may be set. In FIGS. 16A and 16B, the direction parallelto the plane of paper is a Y′-axis and the direction perpendicular tothe plane of paper is a Z′-axis.

FIGS. 17A to 17C illustrate the arrangement of the in-vivo imagescaptured at the time when the capsule endoscope 2 illustrated in FIG.16A passes through positions P51, P52, and P53. The capsule endoscope 2which has passed through the position P51 moves while the axis thereofis substantially parallel to the length direction of the lumen 1 a andthe imaging unit 12 a faces the anus. Therefore, at a position P51′ ofthe lumen model 1 a′ corresponding to the position P51, the capsuleendoscope 2 moves with the imaging unit 12 a facing the moving direction(the positive direction of the X′-axis). Therefore, as illustrated inFIG. 17A, in the image display region 110, an in-vivo image A capturedby the imaging unit 12 a is arranged in a display region 151 disposed inthe moving direction and an in-vivo image B captured by the imaging unit12 b is disposed in a display region 152 disposed in a directionopposite to the moving direction.

The capsule endoscope 2 which has passed through the position P52 moveswhile the axis thereof is substantially perpendicular to the lengthdirection of the lumen 1 a, the imaging unit 12 a faces an inner wall 1b, and the imaging unit 12 b faces an inner wall 1 c. Therefore, at aposition P52′ of the lumen model 1 a′ corresponding to the position P52,the capsule endoscope 2 moves while the imaging unit 12 a faces an innerwall 1 b′ (the negative direction of the Y′-axis) corresponding to theinner wall 1 b and the imaging unit 12 b faces an inner wall 1 c′ (thepositive direction of the Y′-axis) corresponding to the inner wall 1 c.Therefore, as illustrated in FIG. 17B, the in-vivo image B captured bythe imaging unit 12 b is arranged in an upper display region 153 of theimage display region 110 and the in-vivo image A captured by the imagingunit 12 a is arranged in a lower display region 154. At the positionP52, since the two imaging units do not certainly face the movingdirection, the display regions 153 and 154 are vertically arranged inFIG. 17B. When any of the imaging units 12 a and 12 b faces the movingdirection, each of the display regions 153 and 154 shifts in apredetermined direction (the right or left direction) according to themoving direction and posture of the capsule endoscope 2.

The capsule endoscope 2 which has passed through the position P53 moveswith the imaging unit 12 a facing the anus and the inner wall 1 c. Inaddition, in the capsule endoscope 2, the imaging unit 12 a faces thefront side of the plane of paper and the imaging unit 12 b faces therear side of the plane of paper. That is, at a position P53′ of thelumen model 1 a′ corresponding to the position P53, the capsuleendoscope 2 moves while the imaging unit 12 a faces the moving direction(the positive direction of the X′-axis) and the inner wall 1 b′ (thenegative direction of the Y′-axis) corresponding to the inner wall 1 band also faces the front side of the plane of paper (the negativedirection of the Z′-axis) and the imaging unit 12 b faces the rear sideof the plane of paper (the positive direction of the Z′-axis).Therefore, as illustrated in FIG. 17C, the in-vivo image A captured bythe imaging unit 12 a is arranged in a display region 155 disposed inthe moving direction and the in-vivo image B captured by the imagingunit 12 b is arranged in a display region 156 disposed in the directionopposite to the moving direction.

In a case in which the positions of the display regions 155 and 156 areadjusted according to the positional relationship between the imagingunits 12 a and 12 b, when portions of or the entire display regions 155and 156 overlap each other on the screen (that is, the coordinates ofthe imaging units 12 a and 12 b overlap each other in the X′-Y′ plane),a method of overlapping the display regions 155 and 156 is determinedaccording to the values of the Z′-axis coordinates of the imaging units12 a and 12 b. For example, at the position P53′, since the imaging unit12 b is disposed on the front side of the imaging unit 12 a, the displayregion 156 in which the in-vivo image B is arranged overlaps the displayregion 155 in which the in-vivo image A is arranged, as illustrated inFIG. 17C.

As described above, according to the fifth embodiment, the user canintuitively and easily know the three-dimensional posture of the capsuleendoscope 2 with respect to the moving direction (the direction to theanus) of the capsule endoscope 2.

Modification 5-1

In the fifth embodiment, the positional relationship of the capsuleendoscope 2 in the depth direction is displayed by the overlap betweenthe display regions 155 and 156. However, various other methods may beused to the positional relationship. For example, as illustrated in FIG.18, the display region 155 may be reduced such that the imaging unit 12a corresponding to the in-vivo image A which is arranged in the displayregion 155 is disposed on the rear side of the imaging unit 12 b withrespect to the plane of paper. On the other hand, the display region 156may be enlarged. Alternatively, the display region 155 may be reducedand the display region 156 is enlarged.

According to Modification 5-1, it is possible to display the entiredisplay region 155 which is arranged on the rear side on the screen.

Modification 5-2 In the lumen model 1 a′ described in the fifthembodiment, in some cases, the directions in which the imaging units 12a and 12 b capture the in-vivo images A and B and the arrangement of thein-vivo images A and B in the image display region 110 are reversedaccording to the relationship between a change in the posture of thecapsule endoscope 2 due to rotation and the shape of the lumen. In thiscase, the direction of the Y′-axis in the lumen model 1 a′ may beappropriately changed to match the positional relationship between theimaging units 12 a and 12 b at the imaging time with the positionalrelationship between the in-vivo images A and B during display.

Specifically, when the posture determining unit 563 detects, forexample, the reversal of the capsule endoscope 2 in the Y′-axisdirection from information about the position of the capsule endoscope2, the display control unit 57 switches the in-vivo images displayed inthe display regions 153 and 154 based on the position detected by theposture determining unit 563.

For example, as illustrated in FIG. 19A, the capsule endoscope 2 whichhas passed through a position P54 moves with the imaging unit 12 afacing the inner wall 1 b. Therefore, when the in-vivo images A and Bare displayed based on the coordinates in the lumen model 1 a′, thein-vivo image B is arranged in an upper display region 157 and thein-vivo image A is arranged in a lower display region 158, asillustrated in FIG. 19B.

Then, when the capsule endoscope 2 rotates and reaches a position P56through a position P55, the imaging unit 12 a faces the inner wall 1 b,similar to the position P54. Therefore, when the in-vivo images A and Bare displayed based on the coordinates in the lumen model 1 a′, thepositional relationship between the in-vivo images A and B on the imagedisplay region 110 and the positional relationship between the imagingunits 12 a and 12 b at the position P56 are reversed.

When the capsule endoscope 2 rotates, the Y′-axis direction in the lumenmodel 1 a′ is reversed at the time when the axis L is horizontal (thatis, at the time of the position P55). Then, as illustrated in FIG. 19C,the in-vivo image A is arranged in the upper display region 157 and thein-vivo image B is arranged in the lower display region 158. Therefore,it is possible to match the positional relationship between the imagingunits 12 a and 12 b at the position P56 with the positional relationshipbetween the in-vivo images A and B in the image display region 110.

Sixth Embodiment

Next, a sixth embodiment of the invention will be described.

The structure of a capsule endoscope system according to the sixthembodiment is the same as that illustrated in FIGS. 1 to 6. the sixthembodiment is characterized in that the arrangement of in-vivo images onan observation screen is determined based on the coordinates based onthe subject 1.

In this case, a posture determining unit 563 detects the posture of acapsule endoscope 2 at the coordinates (absolute coordinates (X, Y, Z))based on gravity acceleration, based on posture information (see FIG.20A). In addition, the posture determining unit 563 determines theposture of the subject 1, based on the information about the posture ofthe subject 1 which is generated based on a signal detected by the gyrosensor 37 provided in the receiving device 3 of the subject 1 (see FIG.20B). The posture determining unit 563 calculates the relativecoordinates (relative coordinates (x, y, z)) of the capsule endoscope 2with respect to the subject 1 from the posture of the capsule endoscope2 at the absolute coordinates and the posture of the subject 1. Anintraluminal model 160 based on the subject 1 illustrated in FIG. 20B isacquired based on the relative coordinates. When the subject 1 isstanding, the absolute coordinates are identical to the relativecoordinates. When the subject 1 is lying on the side, the plane formedby two axes in the absolute coordinates is rotated 90 degrees to convertthe absolute coordinates into the relative coordinates.

The display control unit 57 determines the arrangement of in-vivo imagesA and B captured by imaging units 12 a and 12 b based on the movingdirection of the capsule endoscope 2 and the positional relationshipbetween the imaging units 12 a and 12 b in the intraluminal model 160acquired by the posture determining unit 563.

For example, the capsule endoscope 2 which has passed through a positionP61 moves with the imaging unit 12 a facing the moving direction (theanus). Therefore, in an image display region 110 illustrated in FIG.21A, the in-vivo image A is arranged in a display region 161 disposed inthe moving direction and the in-vivo image B is arranged in a displayregion 162 disposed in a direction opposite to the moving direction.

The capsule endoscope 2 which has passed through a position P62 moveswith the imaging unit 12 a up. Therefore, in the image display region110 illustrated in FIG. 21B, the in-vivo image A is arranged in an upperdisplay region 163 and the in-vivo image B is arranged in a lowerdisplay region 164. In this case, the in-vivo image arranged in theupper display region 163 corresponds to the upper wall of the lumen 1 aand the in-vivo image arranged in the lower display region 164corresponds to the lower wall of the lumen 1 a.

The capsule endoscope 2 which has passed through a position P63 moveswith the imaging unit 12 a facing the front side of the plane of thedrawing. Therefore, in the image display region 110 illustrated in FIG.21C, the in-vivo image A is arranged in a front display region 165 andthe in-vivo image B is arranged in a rear display region 166. In thiscase, for example, the front display region 165 corresponds to theabdomen of the subject 1 and the rear display region 166 corresponds tothe back of the subject 1.

As described above, according to the sixth embodiment, the arrangementof the in-vivo images is determined based on the relative movingdirection or posture of the capsule endoscope 2 in the body of thesubject 1. Therefore, the user can three-dimensionally and intuitivelyknow the observation position and direction of a part of the body of thesubject 1 in the in-vivo image.

In addition, in the sixth embodiment, the front display region issuperimposed on the rear display region. However, similarly toModification 5-1, the front display region may be enlarged or the reardisplay region may be reduced. Alternatively, the front display regionmay be enlarged and the rear display region may be reduced.

Modification 6-1

In the sixth embodiment, the posture of the subject 1 is determinedbased on the signal detected by the gyro sensor 37 provided in thereceiving device 3. However, the subject 1 may input information aboutthe posture of the subject 1, such as standing or recumbence. In thiscase, the receiving device 3 may be provided with a posture input unitwhich is used by the patient to input the position information. Theposition input unit may be implemented by, for example, a touch panel oroperation buttons.

When the subject 1 changes the posture during examination using thecapsule endoscope 2 and inputs information about the current posture(posture information such as information about standing or recumbence)using the posture input unit, the signal processing unit 32 associatesthe input posture information with the image data received at that time.Then, the image display 5 can acquire the image data and informationabout the posture of the patient when the in-vivo image is captured.

Modification 6-2

The position information of the capsule endoscope 2 which is separatelyestimated may be displayed on the screen which is generated anddisplayed in the sixth embodiment. In this case, for example, thecontrol unit 56 estimates the position of the capsule endoscope 2 at thetime when each in-vivo image is captured, based on information about thereception intensity of the receiving antennas 30 a to 30 h which isassociated with the image data. Various known methods may be used as aposition estimation method. In addition, the control unit 56 may convertthe coordinates of the estimated position of the capsule endoscope 2into values on the relative coordinates calculated by the posturedetermining unit 563.

The display control unit 57 displays the calculated position of thecapsule endoscope 2 on the image display region 110.

FIGS. 22A to 22C are schematic diagrams illustrating examples of thedisplay of the in-vivo images according to Modification 6-2 and aredifferent from FIGS. 21A to 21C in that a human body model 167 is added.A reduced FIG. 168 of the intraluminal model 160 illustrated in FIG. 20Bis drawn in the human body model 167. The position of the capsuleendoscope 2 corresponding to the time when the in-vivo image which isbeing displayed in the image display region 110 is captured isrepresented by a dot 169 on the reduced FIG. 168.

The user can observe the in-vivo images arranged in the display regions161 to 166 while referring to the position of the capsule endoscope 2 onthe human body model 167 to easily and intuitively know the captureposition and direction of the in-vivo image which is currently beingdisplayed in the body of the subject 1.

Seventh Embodiment

Next, a seventh embodiment of the invention will be described.

In the first to sixth embodiments, the moving direction or posture ofthe capsule endoscope 2 is shown by the position (for example the left,right, upper, and lower sides) of the display region or the overlappingmethod. However, other methods may be used to show the moving directionor posture of the capsule endoscope 2. The structure of a capsuleendoscope system according to the seventh embodiment is the same as thatillustrated in FIGS. 1 to 6.

For example, as illustrated in FIGS. 23A to 23C, when an in-vivo imageon the anus side of the capsule endoscope 2 is arranged in a displayregion 171 and an in-vivo image on the mouth side of the capsuleendoscope 2 is arranged in a display region 172, an icon 171 aindicating the anus side and an icon 172 a indicating the mouth side maybe displayed in the vicinity of the display regions 171 and 172,respectively. In this case, it is possible to improve flexibility in thearrangement of the display regions 171 and 172. For example, the displayregions 171 and 172 may be laterally arranged as illustrated in FIG.23B, or the display regions 171 and 172 may be longitudinally arrangedas illustrated in FIG. 23C.

As illustrated in FIGS. 24A to 24C, when an in-vivo image correspondingto the moving direction of the capsule endoscope 2 is arranged in adisplay region 181 and an in-vivo image corresponding to a directionopposite to the moving direction of the capsule endoscope 2 is arrangedin a display region 182, icons 183 and 184 indicating the movingdirection may be displayed in the vicinity of the display region 181. Inthis case, the user can clearly know the display region 181 in which thein-vivo image corresponding to the moving direction of the capsuleendoscope 2 is arranged.

As illustrated in FIGS. 25A to 25C, when an in-vivo image on the side ofan upper wall 1 d is arranged in a display region 191 and an in-vivoimage on the side of a lower wall 1 e is arranged in a display region192, an icon 191 a indicating the upper wall 1 d and an icon 192 aindicating the lower wall 1 e may be displayed in the vicinity of thedisplay regions 191 and 192, respectively. In this way, it is possibleto improve flexibility in the arrangement of the display regions 191 and192. In this case, as illustrated in FIG. 25C, the positions of thedisplay regions 191 and 192 may be adjusted according to the positionalrelationship between imaging units 12 a and 12 b which capture thein-vivo images arranged in each display region, in addition to thedisplay of the icons 191 a, 192 a. In this case, the user can clearlyand intuitively know the directions (for example, the upper and lowersides) indicated by the in-vivo images which are arranged in the displayregions 191 and 192.

In the first to seventh embodiments, the display of the in-vivo imagesacquired by the capsule endoscope including two imaging units has beendescribed. However, the first to seventh embodiments may be applied to acapsule endoscope including three or more imaging units.

the first to seventh embodiments of the invention are just illustrative,but the invention is not limited to the embodiments. Variousmodifications of the invention can be made according to, for example,the specifications and it will be apparent from the above descriptionthat various other embodiments can be made without departing from thescope and spirit of the invention.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

What is claimed is:
 1. A capsule endoscope system comprising: a capsuleendoscope that includes a first imaging unit which captures an image ina first direction and a second imaging unit which captures an image in asecond direction different from the first direction, is introduced intoa subject, and captures an in-vivo image of the subject; an imagedisplay that displays an image based on image data obtained from thein-vivo images of the subject captured by the first and second imagingunits; a control unit that determines a moving direction of the capsuleendoscope during imaging, specifies one of the first and second imagingunits which faces the moving direction of the capsule endoscope duringimaging, and determines the position of the capsule endoscope; and adisplay control unit that generates a display screen including a firstdisplay region in which an image in the moving direction of the capsuleendoscope is arranged and a second display region in which an image in adirection opposite to the moving direction of the capsule endoscope isarranged, arranges, in the first display region, an image based on theimage data acquired by the imaging unit which is specified to face themoving direction by the control unit, arranges, in the second displayregion, an image based on the image data acquired by the other imagingunit, and changes the positions of the first and second display regionsaccording to the determination result of the position of the capsuleendoscope.
 2. The capsule endoscope system according to claim 1, whereinthe control unit determines the moving direction based on an amount ofmovement of the capsule endoscope when images are captured at differenttimes.
 3. The capsule endoscope system according to claim 1, wherein thedisplay control unit changes the positions of the first and seconddisplay regions in the display screen based on a difference between thepositions of the first and second imaging units along an axisperpendicular to the moving direction of the capsule endoscope.
 4. Thecapsule endoscope system according to claim 1, wherein, when at leastportions of the first and second display regions overlap each other, thedisplay control unit displays the first and second display regions suchthat one of the first and second display regions is superimposed on theother display region, based on the determination result of the positionof the capsule endoscope.
 5. The capsule endoscope system according toclaim 1, wherein, when at least portions of the first and second displayregions overlap each other, the display control unit displays the firstand second display regions such that one of the first and second displayregions is reduced and/on the other display region is enlarged, based onthe determination result of the position of the capsule endoscope. 6.The capsule endoscope system according to claim 1, wherein the controlunit determines the position of the capsule endoscope in a coordinatesystem which has the moving direction as one axis.
 7. The capsuleendoscope system according to claim 1, wherein the control unitdetermines the posture of the capsule endoscope in a coordinate systembased on the subject.
 8. The capsule endoscope system according to claim1, wherein the display control unit displays indicators indicating themoving direction of the capsule endoscope so as to be associated withthe first and second display regions.
 9. The capsule endoscope systemaccording to claim 1, wherein the display control unit displaysindicators indicating the position of the capsule endoscope so as to beassociated with the first and second display regions.
 10. A method ofoperating an image display that displays an image corresponding to imagedata obtained by a capsule endoscope which includes a first imaging unitcapturing an image in a first direction and a second imaging unitcapturing an image in a second direction different from the firstdirection, is introduced into a subject, and captures an in-vivo imageof the subject, the method comprising: determining a moving direction ofthe capsule endoscope during imaging, specifying one of the first andsecond imaging units which faces the moving direction of the capsuleendoscope during imaging, and determining the posture of the capsuleendoscope; generating a display screen which includes a first displayregion in which an image in the moving direction of the capsuleendoscope is arranged and a second display region in which an image in adirection opposite to the moving direction of the capsule endoscope isarranged, and on which an image based on the image data acquired by theimaging unit which is specified to face the moving direction is arrangedin the first display region, an image based on the image data acquiredby the other imaging unit is arranged in the second display region, andthe positions of the first and second display regions are changedaccording to the determination result of the position of the capsuleendoscope; and displaying the generated display screen.
 11. Acomputer-readable recording medium having stored thereon an executableimage display program that causes an image display to display an imagecorresponding to image data obtained by a capsule endoscope whichincludes a first imaging unit capturing an image in a first directionand a second imaging unit capturing an image in a second directiondifferent from the first direction, is introduced into a subject, andcaptures an in-vivo image of the subject and causes a processor toperform: determining a moving direction of the capsule endoscope duringimaging, specifying one of the first and second imaging units whichfaces the moving direction of the capsule endoscope during imaging, anddetermining the posture of the capsule endoscope; generating a displayscreen which includes a first display region in which an image in themoving direction of the capsule endoscope is arranged and a seconddisplay region in which an image in a direction opposite to the movingdirection of the capsule endoscope is arranged, and on which an imagebased on the image data acquired by the imaging unit which is specifiedto face the moving direction is arranged in the first display region, animage based on the image data acquired by the other imaging unit isarranged in the second display region, and the positions of the firstand second display regions are changed according to the determinationresult of the position of the capsule endoscope; and displaying thegenerated display screen.